The present invention relates to a novel compound having an ether group, which can be cured by radical polymerization and a process for producing the same.
Further the present invention relates to a curable composition capable of polymerization by light or heat, more specifically, the present invention relates to a curable composition which can be used in the field of requiring the cured product to have adhesive property or curability in air, such as paint, coating, adhesive and sealing material.
Thermosetting resins and photocurable resins are used as coating materials, paint materials, optical materials and adhesive materials. Curable compositions exhibiting a high curing rate that contain an acrylic acid ester or methacrylic acid ester as a principal component are widely used as thermosetting resins from the viewpoint that the operation efficiency and productivity can be enhanced. In particular, a bifunctional or higher-functional acrylic acid ester or methacrylic acid ester is employed for increasing the polymerization degree of cured resin to thereby increase the hardness of the surface of the cured resin.
However, in the curing of such a polyfunctional acrylic acid ester by radical polymerization, the polymerization is inhibited by oxygen to thereby produce uncured portion with the result that the problem of remaining tack is caused. Moreover, many of the acrylic acid esters exhibit high skin stimulation, so that, also, the problem of toxicity is encountered.
Vinyl ether compounds are known as being a photocurable compound whose skin stimulation is low. The vinyl ether compounds are cured by cationic polymerization, so that they are less susceptible to the polymerization inhibition by oxygen. However, the catalysts for use in the cationic polymerization have such drawbacks that they are deactivated by moisture or bases, they are expensive and the number of varieties thereof is small to thereby limit the number of really available catalysts and many thereof are highly toxic. Further, the radical polymerization of only one kind (single) vinyl ether does not proceed, so that, for example, the method of copolymerizing a vinyl ether and an acrylic material (monomer) is employed for effecting the radical polymerization. However, in this copolymerization, the copolymerizability cannot always be stated as being excellent and, even if the copolymerization by radical polymerization is performed, the production of product with satisfactorily high practicability is limited.
Recently, the use of a propenyl ether as a cationic polymerization material is drawing attention. Crivello et al. reported in J. Macromol. Sci. Part A, A31(9), 1105 (1994) that propenyl ethers exhibited high cationic polymerizability. The propenyl ether compounds have skeletal structures derived from phenols such as bisphenol.
Further, U.S. Pat. No. 4,864,054 reported that an aromatic propenyl ether compound could be used in various applications through the cationic polymerization thereof. This aromatic propenyl ether compound is one having a skeletal structure derived from a phenol such as bisphenol A or hydroquinone or from an ester such as a terephthalic acid ester or an isophthalic acid ester.
However, when the radical polymerization is intended, the problem is encountered such that the radical polymerizability of this propenyl ether alone is as low as that of the above vinyl ether.
The radical polymerization method has advantages in that, as compared with other polymerization methods, the curing time is generally relatively short, the molecular weight can be large, a large variety of radical polymerization initiators are available and their use is easy. Therefore, the radical polymerization method is an industrially useful polymerization method. However, a compound having a propenyl ether group or an allyl ether group whose sole radical polymerization is practicable is little known.
(1) Canadian Patent Specification No. 575985 describes esters prepared from a saturated or an unsaturated polycarboxylic acid and a xcex2-(2-propenoxy)alkanol of the formula RCHxe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x94CH (Rxe2x80x2) CH (Rxe2x80x3)xe2x80x94OH or CH2xe2x95x90C(R) xe2x80x94CH2xe2x80x94Oxe2x80x94CH (Rxe2x80x2) CH (Rxe2x80x3) xe2x80x94OH (wherein each of R, Rxe2x80x2 and Rxe2x80x3 is selected from among hydrogen and alkyls, the alkyls preferably being those which do not contain more than three carbon atoms, for example, methyl, ethyl or propyl).
Specifically, the specification discloses, as preferred esters, di-(xcex2-propenoxyethyl) maleate, di(xcex2-propenoxyethyl) fumarate (CH2xe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x94(CH2)2xe2x80x94OCOxe2x80x94CHxe2x95x90CHxe2x80x94COOxe2x80x94(CH2)2xe2x80x94Oxe2x80x94CH2xe2x80x94CHxe2x95x90CH2) and di-(xcex2-propenoxyethyl) itaconate (CH2xe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x94(CH2)2xe2x80x94OCOxe2x80x94CH(xe2x95x90CH2)CH2xe2x80x94COOxe2x80x94(CH2)2xe2x80x94Oxe2x80x94CH2xe2x80x94CHxe2x95x90CH2). Further, the specification teaches that the copolymerization reaction of the above monomers is accelerated by the presence of a peroxide such as dibenzoyl peroxide or diacetyl peroxide.
However, the specification fails to present any specific description as to esters including an alkylene group having at least 3 carbon atoms or a cycloalkylene group having at least 5 carbon atoms in the moiety xe2x80x9cCH(Rxe2x80x2)xe2x80x94CH(Rxe2x80x3)xe2x80x94xe2x80x9d of the above formula.
(2) Japanese Patent Publication No. 55(1980)39533 discloses a process for producing an xcfx89-vinyloxyalkyl carboxylate in which an unsaturated carboxylic acid and an xcfx89-halogenoalkyl vinyl ether are condensed with each other.
(3) Further, Japanese Patent Laid-open Publication No. 57(1982)-165409 discloses a thermosetting composition containing a thermosetting catalyst, which comprises:
(A) an aromatic polyvinyl ether compound selected from among (i) polyvinyl compounds of the formula R[QR1OC(R2)xe2x95x90C(R3)2]n (wherein Q: xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94, etc., R: polyvalent aromatic organic group, R1: alkylene group having 1 to 8 carbon atoms, each of R2 and R3: H or alkyl group having 1 to 8 carbon atoms, and n: 2 to 10) and (ii) reaction product of the above polyvinyl compound with an active hydrogen compound selected from a specified group including polycarboxylic acids, phenols, etc., and
(B) (a) an aryl onium salt selected from a specified group and (b) an organic oxidant or an aromatic polyvinyl ether soluble copper compound.
(4) Still further, Japanese Patent No. 2,744,849 describes a process for producing a polyester having vinyl ether terminals, which comprises the steps of:
(a) reacting a polyol with a polybasic acid ester having vinyl ether terminals in the presence of a transesterification catalyst to thereby produce an oligomer of the polyol and the polybasic acid ester which has vinyl ether terminals and a by-product of hydroxymonovinyl ether, and
(b) separating the hydroxymonovinyl ether during the reaction of the step (a).
Compounds of the formula Yxe2x80x94[COOX]m (wherein Y: alkyl group, etc., X: alkyl having 1 to 6 carbon atoms, etc., and m is 2 to 6) in which Y may be xe2x80x94(CH2)nxe2x80x94 are described as the above polybasic acid ester. The reaction of the formula:
XOCOxe2x80x94Yxe2x80x94COOX (i) +Rxe2x80x2CHxe2x95x90CRxe2x80x3OZxe2x80x94OH (ii)xe2x86x92
Rxe2x80x2CHxe2x95x90CRxe2x80x3OZxe2x80x94OCOxe2x80x94Yxe2x80x94COOxe2x80x94ZORxe2x80x3Cxe2x95x90HCRxe2x80x2 (iii)+2XOH↑
(wherein each of Rxe2x80x2 and Rxe2x80x3: H or lower alkyl group having 1 to 10 carbon atoms and Z: alkylene group or cycloalkylene group) and the chain extension reaction between vinyl ether terminated ester (iii) and polyol (HOxe2x80x94Axe2x80x94OH) are described as examples of the vinyl ether terminal forming reactions of ester.
However, in the patent specification, there is no description regarding compounds wherein Y represents xe2x80x94CHxe2x95x90CH or xe2x80x94(CH2)xe2x80x94C(xe2x95x90CH2)xe2x80x94, and there is no description teaching or suggesting the radical polymerization of vinyl ether terminated ester (iii).
(5) Still further, claim 1 of Published Japanese Translation of PCT Patent Application No. 5(1993)-506838 describes an optical fiber coating composition comprising a product obtained by reacting together (a) a vinyl ether urethane oligomer composed of a product obtained by reacting together (i) a hydroxyl terminated polyester or hydroxyl terminated polyether, (ii) a diisocyanate or a polyisocyanate having at least two functional groups and (iii) a hydroxymonovinyl ether, (b) a vinyl ether terminated ester monomer and (c) a vinyl ether terminated monomer derived from a specified alcohol. Axe2x80x94(xe2x80x94COOZOCR4xe2x95x90CHR3)n (wherein n: 1 to 4, A: alkylene group, etc., Z: alkylene, etc., each of R3 and R4: H or alkyl group having 1 to 10 carbon atoms) is described as representing the above vinyl ether terminated ester monomer (b). In claim 3 thereof, xe2x80x94CHxe2x95x90CHxe2x80x94, etc. are listed as the above A, and xe2x80x94(CH2)4xe2x80x94Oxe2x80x94(CH2)4xe2x80x94, xe2x80x94(CH2)4xe2x80x94Oxe2x80x94(CH2)4xe2x80x94Oxe2x80x94(CH2)4xe2x80x94, xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, etc. are listed a the above Z. The specification also describes a composition comprising the above composition and a cationic polymerization initiator, etc.
However, although the specification describes an embodiment in which a cationic polymerization is performed with the use of a cationic photoinitiator of a triarylphosphonium hexafluorophosphate salt (Ar3SPF6) (Union Carbide UVI-6960), there is no example performing the radical polymerization of the vinyl ether terminated ester monomer (b). As apparent therefrom, the specification neither describes any technical concept of effecting the radical polymerization of the above vinyl ether terminated ester monomer (b) nor suggests any technical concept of adding a radical polymerization initiator to the above composition containing the monomer (b) to thereby carry out the radical polymerization.
In addition to the above, in general, radical polymerization by light or heat is predominantly used for curing a curable resin as a covering material such as coating, and particularly from the standpoint of profitability, high-speed photopolymerization by ultraviolet rays (UV) is recently performed.
As the curable resin, an acrylic or unsaturated polyester-type resin is usually used.
The acrylic resin can be cured by the UV curing within a relatively short time and therefore, is applied to various UV curing materials such as paint or coating. According to general techniques, an acrylate-type monomer is often blended to the resin before the curing so as to reduce the viscosity of the acrylate-type oligomer or acrylic resin. However, the acrylate-type monomer is disadvantageous in that the monomer is highly irritative on skin, the curing is prone to polymerization inhibition by oxygen, and tackiness is easily generated at the formation of a thin film of a few microns.
In the case of the unsaturated polyester resin, a styrene monomer is used as a reactive diluent for the unsaturated polyester, however, the styrene monomer is heavily odorous and causes a problem in working. Accordingly, a non-styrene type reactive diluting monomer is demanded.
As the reactive diluent capable of overcoming such a problem, non-acrylate type materials are drawing an attention. Representative examples of the non-acrylate type materials include N-vinylpyrrolidone and vinyl ethers.
The N-vinylpyrrolidone as a monofunctional monomer is low in the skin irritation and excellent in the diluting ability and curability. Furthermore, in the case of using the resin as a covering material, high adhesion to a substrate such as a plastic or a metal can be attained.
The vinyl ethers are used as a curing material in the cationic polymerization system but since radical polymerization scarcely proceeds in the vinyl ethers itself used alone, they are not so often used as a material for radical polymerization. However, Proceedings of RadTech North America Conference, P167 (1992) has reported that a maleic ester and a vinyl ether are successfully copolymerized. Furthermore, it is known that polymerization of a vinyl ether proceeds also with an acryl group though the copolymerizability is low.
Vinyl ethers have a low viscosity and excellent diluting ability and when they are cured, high adhesion to the substrate can be attained. However, vinyl ethers commonly used as a cross-linking agent is mainly a bifunctional vinyl ether such as trimethylene glycol divinyl ether and cyclohexanedimethanol divinyl ether, and these vinyl ethers are low in the radical polymerizability by themselves. Accordingly, in the blending system with an unsaturated polyester, incomplete polymerization of the vinyl ether group and in turn low cross-linking degree result and this adversely affects the physical properties of the cured product. Also, in the blending system with an acrylate, unreacted vinyl ether groups remain to fail in attaining a sufficiently high cross-linking degree, as a result, the surface hardness is liable to decrease.
The present invention has been made with a view toward resolving the above problems of the prior art, and it is an object of the present invention to provide an alkenyl ether compound, especially a 1-alkenyl ether compound such as a propenyl ether compound and a 2-alkenyl ether compound such as an allyl ether compound capable of radical polymerization.
It is another object of the present invention to provide a process for producing the above alkenyl ether compound for use in radical polymerization.
The further object of the present invention is to provide a curable resin which is prevented from oxygen inhibition in the radical polymerizable resin at the curing and yields a cured product having excellent surface hardness and good adhesion to the substrate.
The 1-alkenyl ether compound for use in radical polymerization according to the present invention is represented by the formula:
R1xe2x80x94CHxe2x95x90CHxe2x80x94OR2)nxe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94(R2O)nxe2x80x94CHxe2x95x90CHxe2x80x94R1xe2x80x83xe2x80x83(1)
wherein X represents xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94CH2xe2x80x94C(xe2x95x90CH2)xe2x80x94,
each of Rxe2x80x2 independently represents hydrogen or an alkyl group having 1 to 3 carbon atoms,
each of R2 independently represents an alkylene group having 2 to 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms, and n is an integer of 1 to 10.
In the present invention, it is preferred that, in the formula (1), each of R1 represents CH3.
In the present invention, it is preferred that, in the formula (1), n=1 and each of R2 represents xe2x80x94CH2xe2x80x94CH2xe2x80x94 or xe2x80x94CH2xe2x80x94CH(xe2x80x94CH3)xe2x80x94.
Further, in the present invention, it is preferred that, in the formula (1), n=1, each of R2 represents xe2x80x94CH2xe2x80x94CH2xe2x80x94 or xe2x80x94CH2xe2x80x94CH(xe2x80x94CH3)xe2x80x94, and X represents xe2x80x94CHxe2x95x90CHxe2x80x94(trans).
The first process for producing the 1-alkenyl ether compound for use in radical polymerization according to the present invention comprises subjecting: an ester represented by the formula R3xe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94R4 (wherein X represents xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94CH2xe2x80x94C(xe2x95x90CH2)xe2x80x94 and each of R3 and R4 independently represents an alkenyl group or alkyl group having 1 to 3 carbon atoms) and
an alcohol represented by the formula R1xe2x80x94CHxe2x95x90CHxe2x80x94(OR2)nxe2x80x94OH (wherein R1, R2 and n are the same as mentioned above.)
to a transesterification reaction conducted in the presence of a transesterification catalyst to thereby obtain the above 1-alkenyl ether compound.
The second process for producing the 1-alkenyl ether compound (provided that R1 is not hydrogen) for use in radical polymerization according to the present invention comprises isomerizing a 2-alkenyl ether compound represented by the formula:
R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94(R2O)nxe2x80x94CH2xe2x80x94CHxe2x95x90CHxe2x80x94R5xe2x80x83xe2x80x83(2)
wherein X, R2 and n are the same as mentioned above, and each of R5 independently represents hydrogen or an alkyl group having 1 to 2 carbon atoms,
to thereby obtain the above 1-alkenyl ether compound.
The third process for producing the 1-alkenyl ether compound (provided that R1 is not hydrogen) for use in radical polymerization according to the present invention comprises subjecting:
(i) at least one carboxylic acid or anhydride thereof selected from the group consisting of maleic anhydride, maleic acid, fumaric acid, itaconic acid and itaconic anhydride, and
(ii) an alcohol represented by the formula R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OH (wherein R2, R5 and n are the same as mentioned above) to an esterification reaction conducted in the presence of an esterification catalyst to thereby obtain the 2-alkenyl ether compound of the above formula (2), and isomerizing the 2-alkenyl ether compound to thereby obtain the above 1-alkenyl ether compound.
The fourth process for producing the 1-alkenyl ether compound (provided that R1 is not hydrogen) for use in radical polymerization according to the present invention comprises subjecting:
an ester represented by the formula R3xe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94R4 (wherein X, R3 and R4 are the same as mentioned above) and
an alcohol represented by the formula R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OH (wherein R2, R5 and n are the same as mentioned above)
to a transesterification reaction conducted in the presence of a transesterification catalyst to thereby obtain the 2-alkenyl ether compound of the above formula (2), and
isomerizing the 2-alkenyl ether compound to thereby obtain the above 1-alkenyl ether compound.
In the present invention, it is preferred that the isomerization be performed in the presence of an isomerization catalyst comprising a metal salt, a metal complex, or a catalyst supporting a metal, which metal is at least one metal selected from among the metals of Group 8 of the periodic table.
Further, in the present invention, it is preferred that said isomerization catalyst comprises a metal salt, a metal complex, or a catalyst supporting a metal, which metal is at least one metal selected from among ruthenium, palladium, rhodium, platinum and iridium.
Still further, in the present invention, it is preferred that, in the isomerization of the 2-alkenyl ether compound of the formula (2), a 2-alkenyl ether group be isomerized into a 1-alkenyl ether group corresponding thereto at a conversion of at least 50%.
The 2-alkenyl ether compound for use in radical polymerization according to the present invention is represented by the above formula (2), wherein, provided that it is preferred that, when n=1, each of R2 independently represents an alkylene group having 3 or 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms.
The first process for producing the 2-alkenyl ether compound for use in radical polymerization according to the present invention comprises subjecting:
(i) at least one unsaturated dicarboxylic acid or anhydride thereof selected from the group consisting of maleic anhydride, maleic acid, fumaric acid, itaconic acid and itaconic anhydride, and
(ii) an alcohol represented by the formula R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OH (wherein R2, R5 and n are the same as mentioned above, provided that, when n=1, it is preferred that R2 represent an alkylene group having 3 or 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms) to an esterification reaction conducted in the presence of an esterification catalyst,
to thereby obtain the above 2-alkenyl ether compound for use in radical polymerization.
The second process for producing the 2-alkenyl ether compound for use in radical polymerization according to the present invention comprises subjecting:
an ester represented by the formula R3xe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94R4 (wherein X, R3 and R4 are the same as mentioned above) and
an alcohol represented by the formula R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OH (wherein R2, R5 and n are the same as mentioned above, provided that, when n=1, it is preferred that R2 represents an alkylene group having 3 or 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms)
to a transesterification reaction conducted in the presence of a transesterification catalyst to thereby obtain the above 2-alkenyl ether compound for use in radical polymerization.
The process for producing an ether (co)polymer according to the present invention comprises performing a radical polymerization of any of the above 1-alkenyl ether compounds for use in radical polymerization or the 2-alkenyl ether compound for use in radical polymerization in the presence of a radical polymerization initiator to thereby obtain the above (co) polymer.
The curable compositions according to the present invention comprise the 1-alkenyl ether compound for use in radical polymerization represented by the above formula (1) and a compound having two or more ethylenically polymerizable groups other than the above-described ether compound as essential components.
In the curable composition of the present invention, it is preferred that the composition comprises from 5 to 90 wt % of the compound represented by formula (1) and the following components (a), (b) and (c):
(a) an unsaturated polyester obtained by reacting an unsaturated polybasic acid or an acid anhydride with a saturated polybasic acid and a polyhydric alcohol;
1(b) a (meth)acrylate compound having two or more (meth)acryloyl groups in the structure; and
(c) an ethylenically polymerizable monomer (excluding the compounds of formula (1) and component (b)),
[provided that (a)+(b)+(c) is from 95 to 10 wt % and (a)+(b) is not 0 wt %.
Further, in the curable composition of the present invention, in the above formula (1), R1 is preferably CH3, and X is preferably a trans-form of xe2x80x94CHxe2x95x90CHxe2x80x94.
Furthermore, the ehylenically polymerizable monomer (c) is preferably the 2-alkenyl ether compound represented by the formula (2).
Further, at least one (meth)acrylate-type compound (b) is preferably selected from
(i) urethane(meth)acrylate,
(ii) polyester(meth)acrylate obtained by the reaction of a polyhydric alcohol with a polybasic acid or an anhydride, and a (meth)acrylic acid,
(iii) polyether(meth)acrylate obtained by the reaction of a polyhydric alcohol, which is resulted from adding an ethylene oxide or propylene oxide to a hydroxyl group-containing compound, with a (meth)acrylic acid,
(iv) epoxy(meth)acrylate obtained by the reaction of an epoxy compound with a (meth)acrylic acid or a (meth)acrylate having a carboxyl group, and
(v) polyfunctional (meth)acrylate.
The especially preferred curable compositions of the present invention include:
the composition, wherein the 1-alkenyl ether compound represented by formula (1) accounts for from 20 to 80 wt % and the unsaturated polyester (a) accounts for from 80 to 20 wt %;
the composition, wherein the 1-alkenyl ether compound represented by formula (1) accounts for from 10 to 70 wt %, the unsaturated polyester (a) accounts for from 25 to 60 wt %, and the polymerizable monomer represented by formula (2) accounts for from 1 to 30 wt %, provided that (1)+(2)+(a) is 100 wt %; and
the composition, wherein the 1-alkenyl ether compound represented by formula (1) accounts for from 10 to 60 wt %, the (meth)acrylate-type compound (b) accounts for from 10 to 90 wt %, and the polymerizable monomer (c) accounts for from 0 to 30 wt %, provided that (1)+(b)+(c) is 100 wt %.
The 1-alkenyl ether compound for use in radical polymerization, 2-alkenyl ether compound for use in radical polymerization, process for producing these compounds and method of performing radical polymerization of these compounds and curable composition according to the present invention will be described in detail below. In the following description, when the same character is employed in different chemical formulae, it represents the same group or compound unless otherwise specified.
The 1-alkenyl ether compound for use in radical polymerization according to the present invention is represented by the formula:
R1xe2x80x94CHxe2x95x90CHxe2x80x94(OR2)nxe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94(R2O)nxe2x80x94CHxe2x95x90CHxe2x80x94R1xe2x80x83xe2x80x83(1)
wherein X represents xe2x80x94CHxe2x95x90CHxe2x80x94 or xe2x80x94CH2xe2x80x94C(xe2x95x90CH2)xe2x80x94,
each of R1 independently represents hydrogen or an alkyl group having 1 to 3 carbon atoms,
each of R2 independently represents an alkylene group having 2 to 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms, and n is an integer of 1 to 10.
This 1-alkenyl ether compound for use in radical polymerization (1) has 1-alkenyl ether groups (xe2x80x94Oxe2x80x94CHxe2x95x90CHxe2x80x94R1), preferably, propenyl ether groups (xe2x80x94Oxe2x80x94CHxe2x95x90CHxe2x80x94CH3) at both terminals thereof and, in its molecule, has an unsaturated dibasic acid residue (unsaturated dicarboxylic acid radical) represented by the formula xe2x80x94COxe2x80x94Xxe2x80x94COxe2x80x94, such as maleic acid residue (i), fumaric acid residue (ii) or itaconic acid residue (iii), namely, 
The propenyl ether group (xe2x80x94Oxe2x80x94CHxe2x95x90CHxe2x80x94CH3) has E-form and Z-form. In the formula (1), the propenyl ether group may be of either E-form or Z-form, and the ratio thereof is not particularly limited.
When X is xe2x80x94CHxe2x95x90CHxe2x80x94, there are two types, namely cis and trans, and the cis type corresponds to the above formula (i) while the trans type corresponds to the above formula (ii). On the other hand, when X is xe2x80x94CH2xe2x80x94C(xe2x95x90CH2)xe2x80x94, the compound corresponds to the above formula (iii).
Generally, the compound containing a 1-alkenyl ether group exhibits high cationic polymerizability but low radical polymerizability. However, in the present invention, the 1-alkenyl ether group is combined with the unsaturated dibasic acid residue such as maleic acid residue, fumaric acid residue or itaconic acid residue, so that the 1-alkenyl ether group and the double bond of the unsaturated dibasic acid residue exert copolymerizability to thereby enable the radical polymerization. Moreover, in the present invention, there are both 1-alkenyl ether group and unsaturated dibasic acid residue having a double bond in the same molecule, so that a high degree of crosslinking is attained at the time of curing to thereby reduce the proportion of uncured portion with the result that an excellent cured product can be obtained.
In the present invention, the propenyl ether compound of the formula (1) in which R2s are xe2x80x94CH2xe2x80x94CH2xe2x80x94(including both trans and cis, this applies hereinafter) or xe2x80x94CH2CH(CH3)xe2x80x94 and n is 1 is preferred because an excellent cured product is obtained.
In the present invention, the compound of the formula (1) in which X represents the unsaturated double bond derived from fumaric acid xe2x80x94CHxe2x95x90CHxe2x80x94 (trans) is especially preferred. The 1-alkenyl ether group and the double bond derived from fumaric acid are especially excellent in radical copolymerizability.
The above 1-alkenyl ether compound for use in radical polymerization (1) is produced by the following various processes.
Specifically, the 1-alkenyl ether compound (1) can be synthesized by a transesterification of an ester represented by the following formula (4-a) and an alcohol represented by the following formula (4-b):
R3xe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94R4xe2x80x83xe2x80x83(4-a)
wherein X is the same as mentioned above and each of R3 and R4 independently represents an alkenyl group or alkyl group having 1 to 3 carbon atoms, and
R1xe2x80x94CHxe2x95x90CHxe2x80x94(OR2)nxe2x80x94OHxe2x80x83xe2x80x83(4-b)
wherein R1, R2 and n are the same as mentioned above.
The above ester (4-a) is a lower alkyl ester or lower alkenyl ester of an unsaturated dibasic acid (unsaturated dicarboxylic acid) such as maleic acid, fumaric acid or itaconic acid.
This ester (4-a), namely the lower alkyl ester or lower alkenyl ester of an unsaturated dibasic acid, is, for example, one which contains an alkyl or alkenyl group having 1 to 3 carbon atoms. Specifically, for example, the ester (4-a) includes
lower alkyl esters of maleic acid, such as dimethyl maleate, diethyl maleate, dipropyl maleate and diisopropyl maleate;
lower alkenyl esters of maleic acid, such as diallyl maleate;
lower alkyl esters of fumaric acid, such as dimethyl fumarate, diethyl fumarate, dipropyl fumarate and diisopropyl fumarate;
lower alkenyl esters of fumaric acid, such as diallyl fumarate;
lower alkyl esters of itaconic acid, such as dimethyl itaconate, diethyl itaconate, dipropyl itaconate and diisopropyl itaconate; and
lower alkenyl esters of itaconic acid, such as diallyl itaconate.
With respect to the alkyl or alkenyl ester which contains an alkyl or alkenyl group having 4 or more carbon atoms, the removal of by-products from the reaction system tends to be difficult because the boiling point of alkyl alcohol or alkenyl alcohol secondarily produced with the advance of the reaction is high.
The above alcohol (4-b) includes, for example, polyalkylene glycol mono-l-alkenyl ethers in which R2 is an alkylene group and polycycloalkylene glycol mono-1-alkenyl ethers in which R2 is a cycloalkylene group.
Specifically, R1 is preferably CH3, and therefore the preferred examples of the above alcohol (4-b) includes:
polyalkylene glycol monopropenyl ethers in which R2 is an alkylene group, such as ethylene glycol monopropenyl ether, propylene glycol monopropenyl ether, 1,3-propanediol monopropenyl ether, 1,4-butanediol monopropenyl ether, 1,3-butanediol monopropenyl ether, 1,2-butanediol monopropenyl ether, diethylene glycol monopropenyl ether, dipropylene glycol monopropenyl ether, triethylene glycol monopropenyl ether, tripropylene glycol monopropenyl ether, tetraethylene glycol monopropenyl ether and tetrapropylene glycol monopropenyl ether; and
polycycloalkylene glycol monopropenyl ethers in which R2 is a cycloalkylene group, such as 1,2-cyclopentanediol monopropenyl ether, 1,2-cyclohexanediol monopropenyl ether and 1,2-cyclododecanediol monopropenyl ether.
These polyalkylene or polycycloalkylene glycol mono-1-alkenyl ethers (4-b) are preferably used in an amount of 1 to 10-fold mol, still preferably 1.1 to 3-fold mol, relative to the ester group equivalent of the above ester (4-a), namely the ester group equivalent of the lower alkyl ester or lower alkenyl ester of maleic acid, fumaric acid or itaconic acid.
Conventional transesterification catalysts can be used in this transesterification reaction. Examples of preferably used catalysts include:
alkali metals, alkaline earth metals, oxides thereof and weak acid salts of these metals;
oxides, hydroxides, alcoholates, organic acid salts (e.g., zinc acetate) and acetylacetonato complexes of Mn, Zn, Zr, Cd, Ti, Pb, Co and Sn; and
dibutyltin oxide and dioctyltin oxide.
These catalysts are generally used in an amount of 0.01 to 5% by weight, preferably 0.05 to 1% by weight, based on the total amount of the above ester (4-a) such as a lower alkyl or alkenyl ester of maleic acid, fumaric acid or itaconic acid.
The reaction can generally be performed at 80 to 200xc2x0 C., preferably 120 to 180xc2x0 C., under atmospheric or superatmospheric pressure. When the reaction temperature exceeds 200xc2x0 C., a thermal polymerization is likely to occur.
It is preferred that this transesterification reaction be performed in an atmosphere of inert gas such as nitrogen gas.
During the reaction, the polymerization may be prevented by the addition of, for example, the below described phenolic polymerization inhibitor.
The reaction is advanced by distilling secondarily produced alkyl alcohol or alkenyl alcohol off the reaction system. The reaction can be finalized by the removal of secondarily produced alkyl alcohol or alkenyl alcohol under reduced pressure.
The 1-alkenyl ether compound (1) obtained by the above transesterification of ester (4-a) and alcohol (4-b), although can be used as a curable resin while the catalyst remains therein, is occasionally purified before use by, for example, distillation in the presence of the below described polymerization inhibitor.
The propenyl ether compound (1) (with the proviso that R1 is not hydrogen, namely R1 is an alkyl group having 1 to 3 carbon atoms) according to the present invention can be obtained by isomerizing a 2-alkenyl ether compound (2) represented by the formula:
R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94(R2O)nxe2x80x94CH2xe2x80x94CHxe2x95x90CHxe2x80x94R5xe2x80x83xe2x80x83(2)
wherein X, R2 and n are the same as mentioned above, and each of R5 independently represents hydrogen or an alkyl group having 1 to 2 carbon atoms, preferably hydrogen,
to thereby convert 1-alkenyl group to 2-alkenyl group. For example, the allyl ether group xe2x80x9cCH2xe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x9d is converted the propenyl ether group xe2x80x9cCH3xe2x80x94CHxe2x95x90CHxe2x80x94Oxe2x80x94xe2x80x9d to give a propenyl ether compound.
Of these 2-alkenyl ether compounds (2) represented by the above formula (2), it is preferred that, when n=1, each of R2 independently represent an alkylene group having 3 or 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms.
The 2-alkenyl ether compound (2) for use can be obtained by subjecting an unsaturated dicarboxylic acid or anhydride thereof, such as maleic anhydride, maleic acid, fumaric acid, itaconic acid or itaconic anhydride, and an alcohol represented by the following formula (5) to an esterification reaction conducted in the presence of an esterification catalyst.
R5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94(OR2)nxe2x80x94OHxe2x80x83xe2x80x83(5)
wherein R2, R5 and n are the same as mentioned above, provided that, when n=1, it is preferred that R2 represents an alkylene group having 3 or 4 carbon atoms or a cycloalkylene group having 5 to 12 carbon atoms.
The alcohol represented by the above formula (5) has the 2-alkenyl ether group xe2x80x9cR5xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x94xe2x80x9d, preferably the allyl ether group xe2x80x9cCH2xe2x95x90CHxe2x80x94CH2xe2x80x94Oxe2x80x94xe2x80x9d and examples thereof include polyalkylene glycol mono-2-alkenyl ethers in which R2 of the formula (5) is an alkylene group and polycycloalkylene glycol mono-2-alkenyl ethers in which R2 is a cycloalkylene group.
Specifically, R5 is preferably hydrogen, and therefore the preferred examples of the above alcohol (5) includes:
polyalkylene glycol monoallyl ethers in which R2 is an alkylene group, such as ethylene glycol monoallyl ether, propylene glycol monoallyl ether, 1,3-propanediol monoallyl ether, 1,4-butanediol monoallyl ether, 1,3-butanediol monoallyl ether, 1,2-butanediol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, tripropylene glycol monoallyl ether, tetraethylene glycol monoallyl ether and tetrapropylene glycol monoallyl ether; and
polycycloalkylene glycol monoallyl ethers in which R2 is a cycloalkylene group, such as 1,2-cyclopentanediol monoallyl ether, 1,2-cyclohexanediol monoallyl ether and 1,2-cyclododecanediol monoallyl ether.
The above alcohol (5) is used in an amount of 2 to 10-fold mol, preferably 2.1 to 4-fold mol, relative to the unsaturated dicarboxylic acid or anhydride thereof, such as maleic acid, maleic anhydride, fumaric acid, itaconic acid or itaconic anhydride (total amount thereof).
Conventional esterification catalysts can be used in this esterification reaction. Examples thereof include acid catalysts such as p-toluenesulfonic acid, sulfuric acid and acidic ion exchange resins.
With respect to the amount of these catalysts, p-toluenesulfonic acid, sulfuric acid or the like is generally used in an amount of 0.1 to 5% by weight based on the unsaturated dicarboxylic acid or anhydride thereof, such as maleic anhydride, maleic acid, fumaric acid, itaconic acid or itaconic anhydride (total amount thereof). The amount of acidic ion exchange resin used is generally not limited.
This esterification reaction is generally performed at 60 to 150xc2x0 C. under atmospheric or superatmospheric pressure while removing water secondarily produced in accordance with the advance of the reaction.
The esterification reaction may be carried out in a solvent according to necessity. Solvents which form an azeotrope with secondarily produced water and are separated into two layers upon cooling are preferred, examples of which include benzene, toluene and xylene.
The desired 2-alkenyl ether compound (2) can be obtained by removing the catalyst, unreacted starting compound, etc. from the thus obtained reaction mixture solution by alkali washing, water washing, filtration, etc. and occasionally by conducting a purification through, for example, distillation in the presence of conventional polymerization inhibitor.
Further, the 2-alkenyl ether compound (2) can be synthesized by subjecting to a transesterification reaction an ester (4-c) represented by the formula:
R3xe2x80x94OCOxe2x80x94Xxe2x80x94COOxe2x80x94R4xe2x80x83xe2x80x83(4-c)
wherein X, R3 and R4 are the same as mentioned above, and
the alcohol (alcohol (5)) represented by the above formula (5).
This ester (4-c) is a lower alkyl ester or lower alkenyl ester of an unsaturated dicarboxylic acid such as maleic acid, fumaric acid or itaconic acid. The ester (4-c) is, for example, one which contains an alkyl or alkenyl group having 1 to 3 carbon atoms. Specifically, for example, the ester (4-c) includes:
lower alkyl esters of maleic acid, such as dimethyl maleate, diethyl maleate, dipropyl maleate, diisopropyl maleate and diallyl maleate;
lower alkyl esters of fumaric acid, such as dimethyl fumarate, diethyl fumarate, dipropyl fumarate, diisopropyl fumarate and diallyl fumarate; and
lower alkyl esters of itaconic acid, such as dimethyl itaconate, diethyl itaconate, dipropyl itaconate, diisopropyl itaconate and diallyl itaconate. With respect to the alkyl or alkenyl ester having 4 or more carbon atoms, the removal of by-products from the reaction system tends to be difficult because the boiling point of alkyl alcohol or alkenyl alcohol secondarily produced with the advance of the reaction is high.
The alcohol represented by the above formula (5), i.e., polyalkylene glycol mono-2-alkenyl ether or polycycloalkylene glycol mono-2-alkenyl ether having the 2-alkenyl ether group is the same as described above.
The above alcohol (5) is used in an amount of 1 to 10-fold mol, preferably 1.1 to 3-fold mol, relative to the ester group equivalent of the ester (4-c), namely the ester group equivalent of the lower alkyl ester or lower alkenyl ester of unsaturated dicarboxylic acid such as maleic acid, fumaric acid or itaconic acid.
Conventional transesterification catalysts can be used in this transesterification reaction. Examples of preferably used catalysts include:
alkali metals, alkaline earth metals, oxides of these and weak acid salts thereof;
oxides, hydroxides, alcoholates, organic acid salts and acetylacetonato complexes of Mn, Zn, Zr, Cd, Ti, Pb, Co and Sn; and
dibutyltin oxide and dioctyltin oxide.
These catalysts are generally used in an amount of 0.01 to 1% by weight based on the lower alkyl or alkenyl ester of maleic acid, fumaric acid or itaconic acid (total amount thereof).
The reaction can generally be performed at 80 to 200xc2x0 C. under atmospheric or superatmospheric pressure. When the reaction temperature exceeds 200xc2x0 C., unfavorably, polymerization is likely to occur. During the transesterification reaction, the polymerization may be prevented by the addition of a polymerization inhibitor such as a phenolic polymerization inhibitor.
The reaction is advanced by distilling secondarily produced alkyl alcohol or alkenyl alcohol off the reaction system. The reaction can be finalized by the removal of secondarily produced alkyl alcohol or alkenyl alcohol under reduced pressure.
The above 2-alkenyl ether compound (2) is an intermediate (raw material) of the 1-alkenyl ether compound (provided that R1 is not hydrogen) of the formula (1) according to the present invention, as described above. However, this 2-alkenyl ether compound (2) itself can be cured in the presence of a radical polymerization initiator by heat, ultraviolet, electron beam, etc., so that it can be used as a curable resin. In the present invention, from the viewpoint of, for example, the ease of polymerization, it is preferred that the 2-alkenyl ether compound (2) be isomerized for use as the 1-alkenyl ether compound (provided that R1 is not hydrogen) of the formula (1).
The 1-alkenyl ether compound for use in radical polymerization (1) (wherein R1 is an alkyl group of 1 to 3 carbon atoms) is obtained by the isomerization of the thus obtained 2-alkenyl ether compound (2). The isomerization is generally conducted in the presence of a catalyst.
Examples of suitable isomerization catalysts include salts of the metals of Group 8 of the periodic table, complexes thereof having a ligand of, for example, phosphine, nitrile, carbonyl or alkene and catalysts comprising these metals supported on a carrier such as silica, alumina, silica-alumina, active carbon or a metal oxide. These catalysts may be employed either individually or in combination.
In particular, complexes comprising a transition metal such as ruthenium, palladium, rhodium, platinum or iridium among the metals of Group 8 of the periodic table and a ligand of, for example, phosphine, nitrile, carbonyl or alkene and catalysts comprising these metals supported on a carrier such as silica, alumina, silica-alumina, active carbon or a metal oxide are preferred in the present invention.
Specifically, the catalyst of salt of metal of Group 8 of the periodic table is, for example, ruthenium chloride or palladium chloride.
Among the catalysts of complex of metal of Group 8 of the periodic table, ruthenium complexes and palladium complexes are preferred from the viewpoint of isomerization ratio. Specifically, suitable use can be made of, for example,
ruthenium complexes such as dichlorotris(triphenylphosphine)ruthenium, dichlorotetrakis(triphenylphosphine)ruthenium, dihydridotetrakis(triphenylphosphine)ruthenium, chlorohydridotris(triphenylphosphine)ruthenium, carbonylchlorohydridotris(triphenylphosphine)ruthenium and carbonyldihydridotris(triphenylphosphine)ruthenium; and
palladium complexes such as dichlorobis(benzonitrile)palladium, carbonyltris(triphenylphosphine)palladium, dichlorobis(trialkylphosphine)palladium, di-xcexc-chlorobis(xcex7-ethylene)dipalladium, di-xcexc-dichlorobis(triphenylphosphine)dipalladium, tetrakis(triphenylphosphine)palladium, dichloro(1,5-cyclooctadiene)palladium and dichloro(1,3-norbornadiene)palladium. These catalysts can be employed either individually or in combination.
Among the catalysts comprising the above metals supported on carriers, palladium catalysts exhibit high activity. Specifically, palladium/alumina and palladium/active carbon are preferred from the viewpoint of conversion ratio.
Among the above catalysts, the metal salt catalyst and the metal complex catalyst are generally used in an amount of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the 2-alkenyl ether compound (2). The reaction is generally performed at 30 to 250xc2x0 C., preferably 100 to 200xc2x0 C. When the reaction temperature is lower than 30xc2x0 C., the reaction rate is too low. On the other hand, when the reaction temperature exceeds 250xc2x0 C., side reactions may occur.
In the use of the catalysts comprising the above metals supported on carriers, the catalyst supporting 0.05 to 10% by weight of metal is generally used in an amount of 0.01 to 50% by weight, preferably 5 to 20% by weight, based on the 2-alkenyl ether compound (2). The reaction is generally performed at 30 to 250xc2x0 C., preferably 100 to 200xc2x0 C. When the reaction temperature is lower than 30xc2x0 C., the reaction rate is too low. On the other hand, when the reaction temperature exceeds 250xc2x0 C., side reactions may occur.
The isomerization reaction can be performed in an atmosphere of inert gas such as nitrogen gas.
Further, the isomerization reaction can be performed in any of various solvents.
Examples of the solvents include:
aromatic hydrocarbons such as benzene, toluene and xylene;
ethers such as diethyl ether, dimethoxyethane, methoxyethyl ether and tetrahydrofuran;
esters such as ethyl acetate, propyl acetate and butyl acetate;
ketones such as acetone and methyl ethyl ketone; and
alcohols such as methanol, ethanol, isopropyl alcohol and n-butyl alcohol.
A polymerization inhibitor can be added in order to prevent the occurrence of polymerization reaction during the isomerization reaction.
Examples of suitable polymerization inhibitors include:
quinones such as p-benzoquinone and 2,5-diphenyl-p-benzoquinone;
phenols such as hydroquinone, p-t-butylcatechol, 2,5-di-t-butylhydroquinone, mono-t-butylhydroquinone and tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionato]methane; and
metal salts such as copper naphthenate and cobalt naphthenate.
During this isomerization reaction, the isomerization of a maleate to a fumarate may occur depending on the conditions such as the type and amount of catalyst and reaction temperature. In this isomerization reaction, not only a complete isomerization of the maleate to the fumarate may occur but also the isomerization to an isomer mixture consisting of the maleate and the fumarate may result. In the present invention, both of these can be used as the 1-alkenyl ether compound for use in radical polymerization (1). Further, there is no particular limitation with respect to the isomer ratio.
In the isomerization of the 2-alkenyl ether compound of the formula (2), when the ratio of isomerization of 2-alkenyl ether group to the corresponding 1-alkenyl ether group is less than 100%, the obtained isomer has both 2-alkenyl ether group and 1-alkenyl ether group. This compound is also a useful ether compound for use in radical polymerization.
From the viewpoint of the ease of radical polymerization of the ether compound for use in radical polymerization, it is preferred that the ratio of isomerization of 2-alkenyl ether of the formula (2) to 1-alkenyl ether of the formula (1) be at least 50%. This isomerization ratio can be determined by, for example, characteristic peak integral ratio of an allyl ether group vs. propenyl ether group measured by 1H-NMR.
Although the product obtained by the isomerization can be used as it is, occasionally it may be purified before use by, for example, distillation in the presence of a polymerization inhibitor such as a phenol or copper naphthenate.
The thus obtained 1-alkenyl ether compound of the present invention can easily be cured by heating or irradiating it with ultraviolet rays or electron beams to thereby effect a radical polymerization in the presence of a radical polymerization initiator.
A wide variety of radical polymerization initiators can be used without any particular limitation as long as radicals are formed by heat, ultraviolet rays, electron beams, radiation, etc.
Examples of radical polymerization initiators which can be used in the radical polymerization by heat include:
azo compounds such as 2,2xe2x80x2-azobisisobutyronitrile and 2,2xe2x80x2-azobisisovaleronitrile;
ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide and cyclohexanone peroxide;
diacyl peroxides such as benzoyl peroxide, decanoyl peroxide and lauroyl peroxide;
dialkyl peroxides such as dicumyl peroxide, t-butyl cumyl peroxide and di-t-butyl peroxide;
peroxyketals such as 1,1-di-t-butylperoxycyclohexane and 2,2-di(t-butylperoxy)butane;
alkyl peroxyesters such as t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, di-t-butyl peroxyhexahydroterephthalate, di-t-butyl peroxyazelate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate and di-t-butyl peroxytrimethyladipate; and
peroxycarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate and t-butyl peroxyisopropylcarbonate.
These radical polymerization initiators can be employed either individually or in combination.
Examples of radical polymerization initiators which can be used in the radical polymerization by irradiation with ultraviolet rays, electron beams or radiation include:
acetophenones and derivatives thereof, such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropanone-1,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone and derivatives thereof, such as
benzophenones, 4,4xe2x80x2-bis(dimethylamino)benzophenone, 4-trimethylsilylbenzophenone and 4-benzoyl-4xe2x80x2-methyldiphenyl sulfide;
benzoins and derivatives thereof, such as benzoin, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether and benzoin isopropyl ether; and
methylphenyl glyoxylate, benzoin dimethylketal and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. These radical polymerization initiators can be employed either individually or in combination.
These radical polymerization initiators are generally used in an amount of 0.01 to 15% by weight, preferably 0.1 to 10% by weight, based on the weight of the ether compound (1) of the present invention.
The ether compound (1) of the present invention may be blended before use with, for example, an ultraviolet absorber, an antioxidant, a colorant, a filler, a release agent, an antistatic agent and various stabilizers, depending on the object of use.
The 1-alkenyl ether compound (1) for use in radical polymerization according to the present invention can be widely utilized in the field of curable resins, for example, used in:
coating materials for wood coating, film coating, metal coating, plastic coating, inorganic coating, hard coating and optical fiber coating;
paint materials such as paints and printing inks; photoforming materials; optical materials such as optical disks, spectacle lenses and prisms; adhesives; photoresist; sealants; and molding compounds.
When the 1-alkenyl ether compound for use in radical polymerization according to the present invention is utilized in the field of curable resins, it is preferred that the 1-alkenyl ether compound is used in combination with a compound having two or more ethylenically polymerizable groups other than the above-described 1-alkenyl ether compound.
The preferable curable composition comprises from 5 to 90 wt % of the compound represented by formula (1) and the following components (a), (b) and (c):
(a) an unsaturated polyester obtained by reacting an unsaturated polybasic acid or an acid anhydride with a saturated polybasic acid and a polyhydric alcohol;
(b) a (meth)acrylate compound having two or more (meth)acryloyl groups in the structure; and
(c) an ethylenically polymerizable monomer (excluding the compounds of formula (1) and component (b)),
[provided that (a)+(b)+(c) is from 95 to 10 wt % and (a)+(b) is not 0 wt %].
The unsaturated polyester (a) for use in the present invention is a compound obtained by the polycondensation reaction of an unsaturated polybasic acid or an acid anhydride with a saturated polybasic acid and a polyhydric alcohol.
Examples of the unsaturated polybasic acid include maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride. Examples of the saturated polybasic acid used in combination as an acid component include saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid, aromatic polycarboxylic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic anhydride and 2,6-naphthalenedicarboxylic acid, and alicyclic dicarboxylic acids such as bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, 1,2-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride and 1,4-cyclohexanedicarboxylic acid.
Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, 1,3- or 1,4-butanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and 1,6- or 1,9-nonanediol, alicylcic aliphatic diols such as 1,4-cyclohexanedimethanol and tricyclodecanedimethanol, aromatic diols such as ethylene oxide or propylene oxide adduct of bisphenol A, trihydric or greater-hydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol and dipentaerythritol.
The (meth)acrylate-type compound for use in the present invention is a compound having two or more (meth)acryloyl groups in the structure. Specific Examples of (meth)acrylate-type compound include (i) urethane(meth)acrylate, (ii) polyester(meth)acrylate obtained by the reaction of a polyhydric alcohol with a polybasic acid or an anhydride thereof and a (meth)acrylic acid, (iii) polyether(meth)acrylate obtained by the reaction of a polyhydric alcohol, which is resulted from adding an ethylene oxide or propylene oxide to a hydroxyl group-containing compound, with a (meth)acrylic acid, (iv) epoxy(meth)acrylate obtained by the reaction of an epoxy compound with a (meth)acrylic acid or a (meth)acrylate having a carboxyl group and (v) a polyfunctional (meth)acrylate such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate.
The urethane (meth)acrylate for use in the present invention is a known compound and can be obtained by reacting a polyhydric alcohol with polyisocyanate and hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate. Examples of the polyhydric alcohol used here include those described above as the polyhydric alcohol for the unsaturated polyester. Examples of the polyisocyanate include toluene diisocyanate, 4,4xe2x80x2-diphenylmethane isocyanate, xylene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.
Examples of the polybasic acid and polyhydric alcohol used as the starting material of the polyester (meth)acrylate or polyether (meth)acrylate for use in the present invention include those described above for the unsaturated polyester.
With respect to the epoxy compound used as a starting material of the epoxy (meth)acrylate for use in the present invention, epoxy resin-type compounds are known and examples thereof include glycidyl ether and novolak-type glycidyl ether of a bisphenol such as bisphenol A type, bisphenol S type and bisphenol F type.
The ethylenically polymerizable monomer for use in the present invention is a compound having a polymerizable group, exclusive of the compound represented by formula (1) and the component (b). Specific examples thereof include monofunctional (meth)acrylic esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate and isobornyl (meth)acrylate; aromatic vinyl compounds such as styrene, xcex1-styrene, methoxystyrene and divinylbenzene; aliphatic carboxylic vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl stearate and vinyl caproate; alicyclic vinyl esters such as cyclohexanecarboxylic vinyl ester; aromatic vinyl esters such as vinyl benzoate and vinyl t-butyl benzoate; hydroxyalkylvinyl esters such as hydroxyethylvinyl ester, hydroxypropylvinyl ester and hydroxybutylvinyl ester; allyl compounds such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl maleate, diallyl fumarate, diallyl itaconate, diallyl trimellitate, triallyl cyanurate, triallyl isocyanurate, diallyl carbonate, diethylene glycol bisallyl carbonate, trimethylolpropene diallyl ether and pentaerythritol triallyl ether; unsaturated dibasic acids and derivatives thereof such as N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, maleic acid, fumaric acid, maleic anhydride, dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl itaconate and diethyl itaconate; and 2-alkenyl ether compounds represented by formula (2).
Because of insusceptibility to polymerization inhibition by oxygen at the curing, the 2-alkenyl ether compound, especially the allyl ether represented by formula (2) is preferably used in the composition.
These polymerizable monomers may be used individually or in combination.
The amount of the compound represented by formula (1) used in the curable composition is from 5 to 90 wt %, preferably from 10 to 80 wt %. If the amount used is less than 5 wt %, the outstanding effect of improving the adhesion of the cured product to the substrate cannot be brought out, whereas if it exceeds 90 wt %, great curing shrinkage is liable to occur at the curing.
The total amount of (a) the unsaturated polyester, (b) the (meth)acrylate compound and (c) the ethylenically polymerizable monomer used in the composition of the present invention is from 10 to 95 wt %. The components (a) and (b) each has a plurality of polymerizable groups having good copolymerizability with the ether compound of formula (1), such as fumarate or acrylate, therefore, exhibits good curability and in turn a cured product having excellent hardness and good adhesive property can be obtained.
The ether compound of formula (1) for use in the present invention has particularly good copolymerizability with an unsaturated polyester and when the composition comprises from 20 to 80 wt % of the ether compound represented by formula (1) and the balance of an unsaturated polyester, the composition is cured almost without suffering polymerization inhibition by oxygen at the curing and yields a cured product having excellent strength.
Furthermore, even when the polymerizable monomer of formula (2) is added to the composition comprising the ether compound represented by formula (1) and an unsaturated polyester in an amount up to 30 wt %, the composition is cured without suffering polymerization inhibition by oxygen at the curing and yields an excellent cured product.
The ether compound of formula (1) for use in the present invention is also copolymerizable with a (meth)acrylate but a composition containing from 10 to 60 wt % of the ether compound represented by formula (1) with the remaining being a bifunctional or greater functional (meth)acrylate and an ethylenically polymerizable monomer, can yield a cured product having excellent adhesion to the substrate.
The composition of the present invention can be easily cured by heat, ultraviolet rays or electron beam through radical polymerization.
The radical polymerization initiator may be any radical polymerization initiator as far as radicals can be produced, for example, by heat, ultraviolet rays, electron beam or radiation.
Examples of the radical polymerization initiator are the same as mentioned above.
The polymerization initiator is preferably used in an amount of from 0.01 to 15 wt %, more preferably from 0.1 to 10 wt %, based on the weight of the composition of the present invention.
In curable composition of the present invention, depending on the use end, an ultraviolet absorber, an antioxidant, a coloring agent, a lubricant, an antistatic agent and an inorganic filler such as silica, alumina and aluminum hydroxide may be used in combination.
Furthermore, in coating the composition of the present invention, depending on the coating method, a solvent may be used so as to reduce the viscosity. Examples of the solvent which can be used include aromatic hydrocarbons such as toluene and xylene; acetic esters such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethers such as tetrahydrofuran and dioxane; and alcohols such as ethyl alcohol, (iso)propyl alcohol and butyl alcohol.
The composition of the present invention can be widely used in the field of curable resin, for example, as a coating material such as wood coating, film coating, metal coating, plastic coating, inorganic coating, hard coating, optical fiber coating and gel coat agent; a paint material such as paint and printing ink; an optical material such as a photomolding material, optical disk, spectacle lens and prism, an adhesive, a photoresist, a sealant or a molding material. The composition is particularly useful as a thin-film coating material which is susceptible to polymerization inhibition by oxygen. Examples of the substrate on which the composition is coated include a metal, a glass and a plastic. Out of the plastics, polyethylene terephthalate (PET) shows poor adhesion to the coating material coated and therefore, PET is usually surface treated. However, the composition of the present invention exhibits particularly excellent adhesion to PET, accordingly, sufficiently high adhesion can be attained even to an untreated PET.
The novel propenyl ether compound and novel allyl ether compound of the present invention are extremely useful because, as apparent from the Examples, these can be cured by the simple radical polymerization by heat or photoirradiation, and they are applicable for the above various uses such as coating materials, paint materials, optical materials and adhesives.
The present invention provides the process for efficiently and easily producing the above ether compounds.
The cured products obtained by curing the composition of the present invention have excellent tack property (tack free) and excellent adhesion to the substrate, and can be applied to various fields of curable resin.